Liam Lawless (lawless@vignette.freeserve.co.uk)
Wed, 20 Jan 1999 22:46:33 +0000
Hi,
Densities are not equivalent between pyro negs & ordinary negs; Hutchings
suggests setting speed to produce zone I density 0.1 to 0.2 above B+F. Red,
green and blue channels of (colour) densitometer measures these three
components separately, and pyro negs should be read through the blue filter.
Try bleaching a step wedge (in e.g. a sepia toner bleach) and then
redeveloping in PMK to produce a pyro-stained step wedge. Have not myself
tried with a Stouffer, but the Agfatrans gives a good match for Tri-X in
PMK. Then measure its densities and use this, rather than a plain silver
step wedge, for your exposure tests with platinum, etc.
If you haven't got it, you'll find Gordon Hutchings' Book of Pyro useful.
Mine is 1st. edition, but I believe it's now up to the third.
Liam Lawless
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